This invention relates to wastewater treatment and, more particularly, to the removal of industrial contaminants from wastewater to produce a sludge containing the contaminants in a non-leachable condition.
Most types of industries produce wastewater in the course of the manufacturing operation. Various environmental laws regulate the discharge or disposal of the wastewater into natural streams, municipal sewers, land surfaces, or underground reservoirs, since the wastewater usually contains hazardous or undesireable concentrations of contaminants. Generally, these environmental regulations prohibit the concentration levels of the contaminants from exceeding specific limits, which have been determined to ensure a relatively safe and healthy water system.
Many industrial processes, however, produce wastewater that contain contaminants, such as phosphates, heavy metals, nitrates, nitrites, sulfides, sulfites, oils, dyes, fats, arsenic, mercury, or organic compounds, which greatly exceed the prescribed limits for safe disposal. The sludge that results from various industrial and treating methods often endangers the environment, since the sludge contains the contaminants in a highly unstable and leachable condition. Contaminants from unstabilized sludge may leach from the sludge into the surrounding ground water, soil, and streams and, cause environmental damage.
Various methods have been proposed to treat, remove, or stabilize hazardous contaminants contained within wastewater. Unfortunately, these prior methods fail to remove, in a single step, a multiplicity of contaminants in a short amount of time, and to use low cost equipment to produce a sludge having the contaminants in a non-leachable condition. For example, a particular process may remove some contaminants, but the wastewater still requires additional treatment to remove all pollutants prior to the safe discharge of the wastewater. Other methods may remove the contaminants from the wastewater in the form of a sludge, but, the contaminants readily leach from the sludge into the surrounding environment. Typically, many prior treatment techniques require a large expenditure of capital for equipment specifically designed for the particular treatment process. In short, current technology has failed to provide a quick, efficient, relatively inexpensive, and easy to use wastewater treatment process.
The present invention obviates these inherent problems and shortcomings by providing a wastewater treatment method capable of removing a plurality of diverse contaminants from a wastewater system and fixing the contaminants in nonleachable form in a sludge. The present invention achieves a high degree of removal in a quick, efficient, relatively inexpensive, and easy to use method. The present invention is applicable to a number of different industrial wastewater systems. Treatment compositions of the present invention are capable of removing a variety of contaminants, such as phosphates, nitrites, nitrates, sulfides, sulfates, chromium, arsenic, barium, mercury, selenium, cyanide, heavy metals, hexane solubles, such as oil and grease, paints, dyes, latex, starch, and cooling emulsions. In most cases, the present removal system is capable of removing the various contaminants in a single flow treatment, without the need of repetitive treatments. The present process also significantly lowers organic material concentrations in the wastewater as measured by the Biochemical Demand (BOD) or Chemical Oxygen Demand (COD) tests, without adversely affecting the pH of the wastewater system. Additionally, the present technique does not create undesirable carbon or resinous conditions in the treated water.